Registers; Register 231H - Cpu Led Port - Xycom CHIP4e+ User Manual

CHIP4e+ Manual
Serial and parallel port addresses are controlled in the BIOS setup
menus. Changing the setting changes the I/O location.
Serial and parallel port interrupts are available if software does not use
the ports or does not use the interrupt.

Registers

The CHIP4e+ contains three ports: 231h, 233h, and 234h.
Register 231h – CPU LED Port
Register 231h controls the LEDs and signals shown in Table 0-7.
Bit
0
1
2
3
4
5
6
7
18
Note
Note
Table 0-7. Register 231h - CPU LED Port
LED/Signal Result
Reserved 0
DOC2000 EN 0 = Disable
1 = Enable
Reserved 0
Reserved 0
Reserved 0
ENFLASHWR 1 = Enables Flash write
Note: This bit must be 1 to
make Flash visible at D0000h
when booting from AT bus.
VGA_EN 1 = Enables on-board VGA
CLRCMS 1 = CMOS okay
0 = Clear CMOS
R/W
R
R
R
R
R
R/W
R
R